1. Field of the Invention
This invention relates to a radiation image read-out apparatus for use in a radiation image recording and reproducing system. This invention particularly relates to a radiation image read-out apparatus wherein a read-out section and an erasing section are combined integrally.
2. Description of the Prior Art
When certain kinds of phosphors are exposed to a radiation such as X-rays, .alpha.-rays, .beta.-rays, .gamma.-rays, cathode rays or ultraviolet rays, they store a part of the energy of the radiation. Then, when the phosphor which has been exposed to the radiation is exposed to stimulating rays such as visible light, light is emitted by the phosphor in proportion to the stored energy of the radiation. A phosphor exhibiting such properties is referred to as a stimulable phosphor.
As disclosed in U.S. Pat. Nos. 4,258,264, 4,276,473, 4,315,318 and 4,387,428 and Japanese Unexamined Patent Publication No. 56(1981)-11395, it has been proposed to use a stimulable phosphor in a radiation image recording and reproducing system. Specifically, a sheet provided with a layer of the stimulable phosphor (hereinafter referred to as a stimulable phosphor sheet or simply as a sheet) is first exposed to a radiation passing through an object such as the human body to have a radiation image of the object stored thereon, and is then scanned with stimulating rays such as a laser beam which cause it to emit light in proportion to the stored radiation energy. The light emitted by the stimulable phosphor sheet upon stimulation thereof is photoelectrically detected and converted to an electric image signal, and the radiation image of the object is reproduced as a visible image by use of the image signal on a recording material such as a photographic film, a display device such as a cathode ray tube (CRT), or the like.
In the aforesaid radiation image recording and reproducing system, the stimulable phosphor sheet is used to temporarily store a radiation image until the sheet is scanned with stimulating rays to read out the radiation image. Therefore, after the radiation image is read out from the stimulable phosphor sheet, radiation energy remaining thereon should be erased to reuse the sheet.
For satisfying this requirement, it has been proposed to provide a radiation image read-out apparatus with a read-out section for reading out an image stored on a stimulable phosphor sheet, and an erasing section for erasing radiation energy remaining on the sheet.
In the proposed radiation image read-out apparatus, a cassette housing a stimulable phosphor sheet carrying a radiation image stored thereon by use of an external image recording apparatus is fed to a cassette holding section, and the stimulable phosphor sheet is taken out of the cassette and sent to the read-out section for reading out the radiation image. After the image read-out is finished, the sheet is sent to the erasing section where radiation energy remaining on the sheet is erased. The erased sheet is taken out of the read-out apparatus and reused for image recording. In general, a plurality of the erased reusable sheets are stacked in a stacking tray inside of the read-out apparatus, and taken out of the read-out apparatus in the form housed in the stacking tray. Since the sheets stacked in the stacking tray should be housed one by one in a cassette as mentioned above when they are to be reused for image recording, it is necessary to load the sheets one by one into a cassette prior to image recording. Though loading of the sheet into the cassette is carried out by use of a special-purpose loader or manually, the cost of the overall system increases in the case where the special-purpose loader is used, and manual loading is disadvantageous from the viewpoint of sheet processing since the sheet must be touched directly with the hand.
One approach to the elimination of the aforesaid drawbacks is to eliminate the necessity of conducting the aforesaid loading operation by directly conveying the stimulable phosphor sheet into the cassette after the sheet taken out of the cassette is sent to the read-out section and the erasing section and image read-out and erasing are conducted on the sheet. However, with the conventional read-out apparatus, the cassettes are loaded one by one to the cassette holding section. Therefore, in the case where the sheet is returned into the cassette as mentioned above, after a first cassette is loaded into the read-out apparatus, the next cassette cannot be loaded into the apparatus until the sheet is taken out of the first cassette, subjected to image read-out and erasing, and then housed in the first cassette. Thus the operations for loading the cassettes to the apparatus become complicated. Specifically, in many cases, the aforesaid read-out apparatus must conduct the processing of a plurality of the sheets continuously. Particularly, in the case where image recording is conducted continuously in the image recording apparatus and the cassettes housing the sheets carrying a radiation image stored thereon are sequentially sent to the read-out apparatus, it is necessary to exchange the cassette loaded to the read-out apparatus each time the processing of a single sheet is finished in the read-out apparatus in order to operate the read-out apparatus efficiently. Accordingly, the operator of the read-out apparatus must, for example, stand by holding the next cassette housing the sheet carrying a radiation image stored thereon. As a result, the time used for exchanging of the cassettes becomes long, and the cassette exchanging operations become complicated and nonefficient.